DE1571818A1 - Thermal copying process - Google Patents

Description

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AGFA-GEVAERtAG _1571818

PATENT DEPARTMENT LEVERKUSEN .

Re-written from April 1969

Thermal copying process

The invention relates to a method for recording information by means of image-wise reflected electromagnetic radiation on a material that contains substances, that convert light into heat.

Processes are known by which photographic silver halide emulsion layers using the Herschel effect; by image-wise tanning hardening of the recording layer and by means of an adhesive which has been incorporated into either the recording layer or the paraffin layer of a hectographic copier paper by pressing together with the copier paper into a hectographic printing form. The production of hectographic printing forms in this way is mainly complicated by the fact that to produce the hereche; 1 effect, two exposures are necessary, that the development of exposed silver halide layers is relatively expensive, and that, according to the known processes, an adhesive is necessary for the transfer of the hectographic dye to the recording material. Such disadvantages are avoided by "moderate methods" according to the invention.

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009883/0363

be a picture or a stencil that has or has locations that absorb electromagnetic radiation. While the exposure becomes so an original bit of its back in Eontakt Bit a material or in "!! Indirect Iahe a material that reflects visible light. This subheading also includes originals in which parts of the picture and the base of the picture reflect visible light, with the * differ in reflection but are large enough to be one to achieve useful image-wise differentiation.

According to the present process, the pictorial Differences in the degree of swelling of the layer consisting mainly of gelatin (hereinafter referred to as "gelatin layer") used for reproduction purposes below. The gelatin layer, which after exposure to water or an »aqueous system is moistened, then shows a gelatin relief image that can be used for the production of printing forms. Compartment of an embodiment using unhardened gelatin the swollen gelatin layers corresponding to the thermal image can be transferred to a receiver sheet. if the gelatin is hardened to a certain extent only the moisture absorbed in the swollen parts of the layer is transferred.

Sb is to be emphasized that the heat acting during the exposure to the gelatin-containing recording layer, results solely from the converted by the above-mentioned substances and that no light absorbed by dtn image areas of the original heat to the layer so _ \

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It is transmitted that their solubility and their swelling capacity in water change.

In this context, it was observed that when using short exposure times (shorter than 10 "see) the gelatin-containing recording layer during exposure can have contact with the light-absorbing areas of the original. Although the image areas are to a certain extent in a thermally conductive connection with the gelatin layer 1 a, they do not heat the gelatin, or at least not effectively. It can thus be seen that the present recording method is in no way limited in scope the contact between the original and the gelatin-containing layer during exposure depends.

According to one embodiment of the method, the Virtually completely eliminate heat transfer from the image areas of the original to the recording layer. In addition is placed between the recording layer and the original a material with poor thermal conductivity, for example a paper backing or a resin layer.

When using the Reflexbellchtungsverfaihrens such a Layer or base, of course, must be permeable to the copying light.

Increasing the temperature of the gelatin to 50 to 200 ⁰ G significantly increases the tendency of the gelatin to swell in water. The gelatine is in the self-state before heating

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However, heating it changes the structure and then resembles a _dried% gelatin as a sol, such as a gelatin which has been dried at temperatures higher than 35 to 40 ⁰ G.

The different swelling of the gelatin layer can be observed directly when the layer is moistened with water. The tendency of gelatine to swell changes calibrate with their degree of hardness. After exposure, an essentially uncured gelatin layer will that can be completely washed out with water at 25 ° C and will be suitable for the production of gelatine transfer images. In contrast, one becomes in the same way exposed hardened gelatin layer the increased swelling, tendency merely as the difference in the degree of swelling between the areas heated by the absorbed, reflected light and reveal the areas that are not or only slightly exposed. This becomes clear when you look at the gelatin θ chichi immersed in an aqueous dye solution for a few seconds, with the dye solution is absorbed by the heated layer areas and a dye image is created.

Hectographic printing forms can be produced in various ways from a gelatin relief image as described above.

One way of producing hectographic printing forms is to use a heat-sensitive gelatin layer, see below use, which contains a water-insoluble hectare graphic dye or a reaction component, which iur the formation,

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• is capable of a hectographic dye. Subject to reflex exposure, the gelatin parts, which have been heated by reflected and absorbed light, are ^{washed out with water at a temperature between 20 and 30 °} C., leaving a reversed gelatin relief image. The material thus obtained can be used as a hectographic printing plate.

In another embodiment, the reversed gelatin relief is pressed against a hectographic carbon paper, as it is, for example, for the method according to FIG Canadian patent 666 600 is used. Compartment • in a few seconds the two materials are separated again, wherein a layer of the dye layer of the carbon paper the reverse gelatin relief image remains. The material that makes up the transferred parts of the dye layer can now be used as a hectographic printing form.

In a further embodiment, a hectographic form for producing negative prints is created by transferring the swollen gelatin parts onto a receiving sheet. The gelatin pieces can be colored before or after the transfer. The transfer may be done by application of pressure, advantageously between two rollers, one of which is heated in • · to a temperature between 30 and 50 ⁰ C. The two materials are then separated after leaving the pair of rollers.

• ORIGIMATE BATHROOM

For the production of printing forms, in which τοη image-wise Xdpophll- Hydrophilunter differentiated use is made, a layer of swollen gelatin or a gelatin layer, which remains after washing out the swollen parts, can be transferred to a hydrophobic or a hydrophilic lithographic base. As a hydrophilic base For example, a grained zinc or aluminum mix film or a paper coated with Xasiin is suitable. When a If a hydrophilic base is used, the transferred gelatin must be rendered hydrophobic.

The printing form produced in this way can be used for all conventional lithographic processes are used, those with lipophilic inks in conjunction with a dampening system or as described in Belgian patent 676,898 work with hydrophilic inks.

Purely for the production of screen printing forms or stencils, the swellable gelatine can be in or on the surface of a suitable base. For this purpose, Japanese paper (Yoshino paper) is particularly suitable, Hylon mesh with a mesh size of 0.2 to 0.08 mm and fabric made of bronze wires · The stencil can be prepared for printing by washing out the image-wise heated gelatin parts to get prepared. But it is also possible to create the stencil by transferring a layer of moist, swollen gelatin on an uncoated sieve material to manufacture. The sieve openings are closed in the same way as the picture. To the mechanical strength of the

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Stencil su verbeesem, the transferred gelatin can subsequently hardened.

Various types of gelatin can be used for the production of the heat-sensitive recording material B. So it was found that both gelatins with lower Bloom number, as well as those with a Bloom number over 200 deliver practically usable picture differences. Gelatin layers suitable for the process according to the invention become in British Patent 985,833. Of the The term "gelatin" in the present context includes gelatin derivatives as used in the Belgian patents 484 324 * 606 122 and 608 566 can be specified.

Trap. Of one form more than one gelatin relief transfer image is to be produced, it is expedient to use an essentially unhardened gelatin and the transfer printing in Presence of a gelatin-tanning aganza such as ~ aluminum sulfate, chrome alum, potash alum, formaldehyde, Chromium chloride, glyoxal or tannic acid. The hardening agents are generally added to the aqueous dampening liquid. This procedure makes it possible • to make a large number of transfers.

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According to a special embodiment, a gelatin bath is used which is covered with a metal saw, for example Has been hardened with aluminum sulfate, which is later removed, so that an uncured gelatin results. The gelatin is in this case preferably treated by treatment with a complexing agent for the metal ions of the hardening agent.

The complexing agent is added to the moistening liquid. After treatment with this liquid, the Gelatin can be transferred from the heated and more swollen areas of the layer.

In one preferred for the method according to the invention On the recording material, the gelatin layer, which contains the heat-sensitive substances, is applied to a non-heat-conducting base, such as a cellulose triacetate film. The optical density of the gelatin layer should be between 0.3 and 0.8, taking into account the copying light used. In other words, at least 20 # and at most 80 # des Copy light should be transmitted by the recording material and reach the reflective original.

The gelatin layer should mainly consist of gelatin, (preferably from more than 80% by weight gelatin). You can about it also contain certain amounts of dissolved and / or dispersed substances, with the proviso that these substances do not affect the desired swelling ratios of the layer or only have an insignificantly unfavorable effect. For example, the following substances can be contained in the gelatin layer:

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dyes, catalysts or reaction components for the Dye formation, protective colloids for the dispersed substances used, reducing substances, developing substances for silver halides, finely divided, etchable metals, development nuclei for complex silver halides, light-sensitive Substances, plasticizers, hygroscopic compounds, such as GIyζeröl, 1,5-hexanediol and magnesium chloride, as well as hardening reagents in latent form.

The concentration of these additives in the heat-sensitive layer or in the layers or films that form part of the Forming recording material should not be so high that the heat-sensitive material is too opaque for reflective exposure will.

Ils suitable substances that use visible and infrared light absorb and convert into heat, called selenium the following:

Finely distributed soot, graphite, Prussian blue, oxides, sulfides or carbonates of heavy metals, preferably of those with an atomic weight between 45 and 210, such as manganese or Lead sulfide, further heavy metal powder, such as silver, bismuth, Lead, iron, cobalt and fiekel. The amount of pigments incorporated into the recording material should be such that that an optical density of the layer of 0.2 to 0.8 results.

Regarding the pigments that absorb visible light and convert into heat, see dlt Belgian patent specification 557 and the German patent application .A 52 "494 TXb / 15k

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flat a particular embodiment is the whole During exposure, the surface of the gelatin layer is brought into thermally conductive contact with colored substances that are light absorb a limited part of the visible spectrum and convert it into heat. Its gelatin layer, which is spectrally sensitized in this way, can be used for rendering more colored Originals are used. . - ..

More detailed information on substances that absorb visible light and convert it into heat can be found in the German Patent application .. A 52 494 Ylb / I5k.

It should be noted that mixtures of these colored substances can also be used, so that light of the the entire visible spectrum is absorbed. Furthermore, these substances do not need to be in the visible spectrum to absorb alone, you can also do this in the infrared range. For a good reproduction of red-colored image areas should however, this absorption should be as small as possible.

For the optical sensitization of the gelatin shichi; colored substances or their mixtures used expediently selected so that they absorb light which is at least one of the primary colors (red, green, blue) or Subtractive colors (blue-green, purple, yellow).

Substances that absorb part of the visible spectrum and convert the absorbed light energy into heat

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■ ind, for example, dyes from the class of azo dyes, triaryl methanes, xanthenes, acridines, methine dyes, azine dyes, phthalocyanines, antraquinone dyes and the same.

The substances can be used as dispersions and / or solutions. When used in dispersed form, their grain size should be less than 0.1 Ai «

When using optically sensitized gelatin layers gives the present method the possibility of producing printing forms that are suitable for color printing and for the production of colored multiple copies of a color master.

For this purpose three different materials are used, whose heat-sensitive gelatin layer contains a substance that absorbs red, green or blue light and changes itself heated in the process, for example a gelatin layer, which has a blue-green, a purple btsw. contains a yellow dye. These can be dyes that are suitable for the hectographic duplication process.

The swellability and water solubility of a heat-sensitive gelatin layer which contains a blue-green dye will be increased in those places which correspond to the red areas of the exposed original. Similarly, the layer with a purple dye will respond to the green and the layer with a yellow dye to the blue areas of the original. g ^ -Qp * Qtf

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To produce multicolor prints, the matrices produced in the manner described are made to fit peeled off on top of each other

for one: reproduction of originals, the separate bar * Carrying positions in the pure primary colors blue, green and red (e.g. a letterhead in the colors blue, green and Red) three separate heat-sensitive gelatin layers are used that sensitize to yellow, purple and cyan or contain a blue, green and red dye. By washing out the heated gelatin areas, copies are made in the three primary colors.

The success of recording with visible light depends essentially on the intensity of the radiant energy. For example, a gelatin layer that is exposed when exposed to a light source of certain energy changes its swelling properties in insufficient catfish completely satisfied-, provide positive results if the radiant energy is increased accordingly.

Types of lamps and exposure systems that use electromagnetic Radiation with a proportion of at least 70 56 visible Emit light (in other words, which emit only a small proportion of UY and IR Lient) and those with short Exposure times to provide a high radiation intensity are preferred for the present method. Lamps this Type are so-called flash lamps, more precisely, gas discharge flash lamps. _ ^

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In connection with the present invention, good results are obtained with a xenon gas discharge lamp with energies from 300 to 1000 watts. in periods of 10 ~ ⁴ to 10 ~ ² see. supplies.

according to a preferred embodiment of this invention the gas discharge lamp has the shape of a thin tube,. which is arranged in a hollow glass cylinder, so that a uniform exposure of the recording material that the Outer wall of the cylinder rests, is possible.

Details about a copier which contains such a gas discharge lamp can be found in the Belgian patent 664 868.

It is also possible to have several flashing lights working simultaneously to use or to expose the layer several times with a lamp. In order to achieve optimal illumination, you can Reflectors and other optical aids can be used.

Gas discharge lamps with lower energy can also be used if the emitted energy is focused on a relatively small heat-sensitive area. For example, a gas discharge lamp with an output of 40 watts is suitable. for the illustration of 6 χ 6 ca and 6 χ 9 cm originals on a heat-sensitive β material according to the present invention. Of course, the exposure can be progressive as well be carried out intermittently. In other words, the thermosensitive material can either be a modulated bit

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High intensity light point can be scanned image-wise, for example with a laser beam or it can through • be progressively exposed in a slit through which, for example, the copying light of a continuously radiating tube lamp is focused.

In the first 4 examples that follow, the gelatin layer is in contact with the light-absorbing areas of the original during exposure. Although these places are connected to the gelatin layer in a thermally conductive manner to a certain extent, the gelatin will not or at least not effectively heated. Flash exposure is used. The only effective heating of the gelatin during this Exposure is caused by the light-absorbing substance that is dispersed in the gelatin layer.

example 1

A polyethylene terephthalate pad with a thickness of 0.1 mm and which is provided with an adhesive layer is coated with the following casting solution

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coated (50 g casting solution per m):

450 g of the above aqueous gelatin solution (Bloom number 240) 15 g of a 10% aqueous saponin solution 20 g of a 1Obigen aqueous dispersion of colloidal silver

The layer is dried ^{at 20 ° C.} The copier material has an optical density of 0.3 measured in terms of durometer. As can be seen from FIG. 1, the copying material (19) is applied to a line master with the radiation absorbing points (299.

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and placed on the radiation-reflecting substrate (23), the heat-sensitive gelatine layer (2o) of the template is facing. The pair consisting of the copy material and the original is now around a glass cylinder (24) with a Clamped diameter of θ cm. The support (27) with the adhesive layer (28) and the heat-sensitive layer (20) touches the dumbbell of the glass cylinder (24) · In the direction of the axis of this cylinder is a xenon gas discharge lamp (25) housed, which during the discharge between the electrodes (26) a radiation energy of 610 watts. in 1/2000 see. supplies. The generated beam trough exists to Mainly from visible light.

Times the exposure is immersed in the recording material 2O ⁰ C hot water and gently rubbed. The areas corresponding to the white background of the original are washed out, while the areas (22) corresponding to the image areas of the original are retained.

The gelatin relief obtained in this way is now pressed against the dye layer of a hectographic carbon paper, which does not have a hydrophobic top layer.

After a contact time of about 30 seconds. become the two Layers separated again. In this case, a layer of the dye layer is transferred to the gelatin relief image, so that a Relief image of the original containing dye, rarely reversed arises.

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The material can now be used as a fuel printing form.

Example 2

A cellulose triacetate base with a thickness of 0.12 mm, provided with a gelatin adhesive layer, is coated with the following pouring solution (30 g / m ² ):

200 g of a 10bigen aqueous gelatin solution (Bloom number 150)

200 g of a carbon black dispersion in water 10 g of a 55 * strength aqueous solution of sodium tetradecyl

eulfate
. 95 g of Yasser

The layer is " ^{dried at 20 °} C. and exposed as described in Example 1".

Tray of exposure as the material is immersed in water and pressed against a 14 g / m heavy Japanese paper. After a contact time of about 2 minutes, the two layers will separate from each other separated.

Tray! Drying, the Japanese paper can be used as a stencil.

A positive remains on the cellulose triacetate pad Gelatin image that can be read through the surface.

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Example 3

A 0.1 mm thick polyethylene terephthalate pad that is equipped with a gelatin adhesive layer, is coated with the following casting solution (70 g / m):

450 g of a 10% aqueous gelatin solution (Bloom number 140)

15 g of a 10% aqueous saponin solution 15 g of a 3 # aqueous solution of the sodium salt of a probe product of oleic acid and methyl taurine

1o g pigment green B Pigmosol (CI.10.00έ) 10 g permanent violet R.L. Colanyl dough (CI. 51.300) (Maximum)

The layer is dried ^{at 20 ° C.} The exposure of the heat-sensitive material takes place in the manner illustrated by FIG. The figure shows a heat-sensitive recording material (28), which consists of a pigmen-

oriented gelatin layer (30) on a polyethylene terephthalate pad {29) exists. The element (31) is a graphic color template with black, red, green and blue image areas " The xenon gas discharge lamp (27) supplies light energy ▼ on 1000 watts. in a 1/2000 see. and stands in one Distance of 4 cm from the original.

Although the heat-sensitive layer (30) is in contact with the light-absorbing areas of the original (31), as shown in FIG. vämeeB-sensitive & layer but no effective® heat-conducting connection.

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Following the exposure, the recording material is immersed (2§ warm to 2O ⁰ C water and carefully abgeriehen. Only the black and green image areas remain the original corresponding layer portions obtained. The reversed gelatin relief thus prepared is now pressed onto a transfer paper and by 5 see. Withdrawn again *

In this way, a transfer print is obtained which only reproduces the black and green image areas of the original.

Example 4

A 0.1 mm thick one equipped with a gelatin adhesive layer Polyethylene terephthalate pad is provided with the following Coated casting solution (50g / m):

200 g of a 20 # strength aqueous gelatin solution

(Bloom number 200)
124 g of a 2 # strength aqueous solution of the compound

SO, SO, SO
ι 3 ι 3

O O

ι «

N \ = Q HO-C ⁷ \

HC-CJ C = CH-C C-CH ₃

128 g of a Taigen aqueous solution of the compound

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SO, ha
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35 g of a 5 # strength aqueous solution of the compound

SO-K SO-K

F O = O KO -C \

*. «« H ₃ CC C = CH-CH = CH-CH = CH-C C-CH ₃

.10 g of a 10 # strength aqueous saponin solution 15% of a 3% aqueous solution of the sodium salt a condensation product of oleic acid and methyl

taurine 95 g of water.

The layer is dried and then together with an original as described in Example 3 exposed. The material is then immersed in water at 20 ° C and washes out the areas that correspond to the white background of the original. The gelatin relief thus obtained is pressed aan now against the dye layer of a hectographic Carbon paper that does not have a hydrophobic top layer *

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Tray, a contact time of about 30 see. become the two Layers separated again. Parts of the Transfer the dye layer to the gelatin relief, see above that a reversed image of the original is created that carries dye. The material can be used as an injection form be used.

Example 5

A 0.14 mm thick polyethylene terephthalate pad equipped with a gelatin adhesive layer is coated with the following casting solution (50 g / m ² ):

450 g of a 10% aqueous solution of gelatin (Bloom number 240)

15 g of a 10% aqueous saponin solution 20 g of a 1Obigen aqueous dispersion of colloidal silver

The layer is dried ^{at 20 ° C.}

After drying, the heat-sensitive copying material becomes further processed in the manner shown schematically in FIG. 3. This means that the heat-sensitive layer (33) on the one provided with a gelatin adhesive layer (34) is exposed to light Polyethylene terephthalate support (35) with the flashing light (27) using the reflex method from the opaque original (36).

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After the exposure, the material becomes easy with Moistened with water and pressed with its heat-sensitive layer against a transfer paper. The two materials are fed at a transport speed of about 10 cm / sec. »Like a pair of pressure rollers and then separate them» A thin layer of the heat-sensitive layer is image-wise transferred to the transfer paper. The dye layer of a hectographic carbon paper, which does not have a hydrophobic top layer, is now opposed to the transfer paper carries pressed. After a contact time of about 1 minute, the two layers are separated again. To this In this way, one gets a dye-carrying, reversed one Image of the original on the transfer paper, which can be used as a fuel printing matrix.

BATH ORIGIN

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Claims (15)

Patent claims: 1. Method of recording information by refleographic Exposure of a heat-sensitive recording material consisting mainly of gelatin with visible light, characterized in that a heat-sensitive material is exposed which, in addition to gelatin consists of substances that are in heat-conducting connection with the gelatin and absorb visible light and convert it into heat, the exposure being of short duration and so high intensity that a record is made, which manifests itself in an increase in the swelling and solubility of the gelatin in water. 2. The method according to claim 1, characterized in that the recording material is a heat-sensitive layer is used, in which the absorbent substances are evenly distributed and which is at least 80% by weight Gelatin - exists. *. 3 · Process according to claims 1 and 2, characterized in that that as a recording material a gelatin layer is used, which contains pigments as absorbent substances. 4. The method according to claim 3 _f, characterized in that a gelatin layer is used as the recording material which contains finely divided carbon as an absorbent substance. BAD ORIGj _n »Ζ " ²² " 0 0 9 * 8 8 3/0 3 6 3 5. The method according to claims 1 to 4, characterized marked- ■ ·. r-net states that a recording material is used in which the amount of absorbing substances is such that the material is permeable to at least 20 μ and at most 80 # of the visible light with which the original is exposed. 6. The method according to claims 1 to 5 »characterized in that as a light source for the exposure of the recording .nungsmaterials a strobe light is used. 7. The method according to claim 6, characterized in that a high-intensity discharge lamp is used as the light source is, 'which is filled with an inert gas. 8. The method according to claim 1, characterized in that a layer of swollen gelatin by pressing together the swollen A recording layer bearing gelatin esters with a receiver sheet and then peeling off the recording layer is transferred to the receiving sheet. 9. The method according to claim 1, characterized in that the areas heated and swollen by reflected light the gelatin layer are washed out. 10..Verfahren according to claim 8, characterized in that the transferred gelatin pieces with a hectographic dye to be stained. AG 146 - 23 - ' * BAD QR!?.! K ^! AL 00 9 8 83/0363 11 »Method according to claim 1, characterized in that the swollen gelatin parts are washed out, the recording layer with the remaining gelatin relief against the dye layer of a hectographic carbon paper, • which does not have a hydrophobic protective layer, pressed and the two elements are separated again, whereby the parts of the pigment layer with the relief image come into contact, are transferred to the relief image. 12. The method according to claim 1, characterized in that the swollen gelatin parts are washed out, the recording layer with the remaining gelatin relief image is pressed against a sieve element which is used for production of screen printing forms is used, the gelatine corresponding to the relief image in the screen openings is transmitted. 13. The method according to claims 1 to 12, characterized in that that a gelatin layer is used as the recording material, which adheres to a base which is suitable for visible 'light is permeable. 14. The method according to claims 1 to 3 and 5 to 13, characterized • that the recording material is a gelatin layer which contains substances that absorb light of a certain part of the visible spectrum and convert it into heat. AG 146 - 24 - ' ^BAD or; q _{! Nal} 009 * 883/0363 15. The method according to claim 14, characterized in that a gelatin layer is used as the recording material that contains substances that mainly absorb in the area of one of the primary or subtractive colors. 16. Method according to Claim 1, characterized in that the exposure time does not exceed 10 "seconds. AG 146 · - 25 - ^PAD ™ ^ " 009883/0363